1. Field of the Invention
The present invention relates to a liquid crystal composition which exhibits a cholesteric phase at room temperature and a bistable/reflective type liquid crystal display device provided with the liquid crystal composition.
2. Description of Related Art
Recently, studies have been made to develop reflective liquid crystal displays by using chiral nematic liquid crystal which is produced by adding a chiral agent to nematic liquid crystal to cause the liquid crystal to exhibit a cholesteric phase at room temperature. Such a liquid crystal display operates by switching between a planar state and a focal-conic state in accordance with the level of the pulse voltage applied thereto. The planar state and the focal-conic state can be maintained after the application of the pulse voltage (which is referred to as bistability or non-volatility), whereby the display can be maintained even after stoppage of the application of the voltage.
At present, however, in such a reflective liquid crystal display, the reflectance is low, and the contrast between the planar state and the focal-conic state is not sufficiently high, and liquid crystal displays of this type which are satisfactory in performance such as color purity (excitation purity), etc. are yet to be developed. To this type of liquid crystal displays, it is also important to have a wide temperature compensation range.